This invention relates to collagen and more particularly to macromolecular reconstituted collagen fiber.
"Natural insoluble collagen" as used herein means and refers to collagen which cannot be dissolved in an aqueous alkaline or in any inorganic salt solution without chemical modification and includes hides, splits, and other mammillian or reptilian coverings. More particularly, "natural insoluble collagen" means and refers to the corium which is the intermediate layer of a bovine hide between the grain and the flesh sides.
Collagen constitutes the connective tissue and is the major type of fibrous protein in higher vertebrae. Collagen in its natural state exists in a triple chain helix along with a constant periodicity between aligned triple chains. The triple helical configuration of collagen is sometimes referred to as a fibril and the fibrils align with an axial periodicity of about 640 A.
Although there are several types of collagen, the major type is referred to as "type I" which is the major collagen of skin, bones and tendons. The type I collagen has a chain composition of [.alpha.1(I).sub.2 .alpha.2]. The .alpha.1(I) and .alpha.2 chains are homologous.
In young animals there is little intermolecular and interfibrilar crosslinking which provides for some degree of solubility of the collagen. However, during the aging process both intermolecular and interfibrilar crosslinking occurs, thus making the collagen insoluble.
The use of collagen in substantially pure form has been proposed for many uses including for burn dressings as is disclosed in U.S. Pat. Nos. 3,939,831 and 3,514,518, and similar medical applications as is disclosed in U.S. Pat. Nos. 3,157,524 and 3,628,974, along with its use as an additive to food.
While it has been known that collagen can be purified by the depolymerization of natural insoluble collagen along with subsequent reconstitution, the yields have been somewhat low and the resultant product is not necessarily biologically active.
U.S. Pat. No. 3,637,642 is exemplary of a process for dissolving insoluble collagen and regenerating the fiber.
Further, collagen and related materials have found utility in the food, cosmetic and pharmaceutical fields.
Further, methods have been proposed for solubilizing and reconstituting collagen with the use of enzymes to sever intra- and interfibular bonds such as is disclosed in U.S. Pat. No. 3,034,852. Further, processes have been proposed for converting collagen fibrous masses to sheet-like material such as in U.S. Pat. Nos. 2,934,447 and 2,934,446.
According to U.S. Pat. Nos. 3,939,831 and 3,742,955 medicinal dressings can be prepared from collagen having dispersed therein antibiotics and the like to aid in healing of skin which has been burned.
In accordance with the present invention a process for dissolving and regenerating collagen fiber is provided which removes substantially all impurities from the collagen source and provides a substantially pure collagen product which is biologically active and substantially non-antigenic.